True. The manual (3rd link) is for a VM and it won't match the CV carb. But there's lots of good basics there on how a carb functions, regardless of type. For the CV carb, check out the gallery and search for ucal. To me the video sounds like the carb needs a good clean and tune.

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Suppose I were an idiot, and suppose I were a member of Congress; but I repeat myself. ... Mark Twain2006 AVL Electra

True. The manual (3rd link) is for a VM and it won't match the CV carb. But there's lots of good basics there on how a carb functions, regardless of type. For the CV carb, check out the gallery and search for ucal. To me the video sounds like the carb needs a good clean and tune.

That's what I've thought from the start. The bike needs a thorough, from square one, going through & tuneup.

That's why I hesitate sometimes to get into discussions with folks who have bought used bikes & maybe aren't really familiar with the basics (or just don't want to hear the truth). They say "The bike is farting or sounds funny & dies all the time. What do you suggest"

They seem to want some overarching "solution" that requires them to turn one screw or something when what needs to be done is get back to square one so you'll have a baseline. If the bike is used & you don't have a Specific History from the P.O. you've got to go through EVERYthing. Pull the plug - put a new one in. Pull the carb. Take it apart (go online & read EVERYthing). See where the needle is set, see what pilot & main are in it. Clean it, pet it, hug it, learn it. Set the valves (again. Go online & learn how to do it. It's not rocket surgery or magic), buy manuals. Study them in bed at night. Immerse yourself in the bike.

There usually ain't no one simple answer to these "it ain't runnin' right" questions. No magic bullet. You can't usually do "just one thing" with an unfamiliar bike that's not running right. And if you don't know the basics of the bike & how it works (& haven't even read any manuals or basic engine books) you're going to be at the mercy of dealers or people who are guessing the same as you are. And you're also not going to completely understand some of the answers you get on this forum. I've seen threads get so convoluted from the original question that you can't make any sense out of them any more.

Sorry to ramble on, but I just had to get that off my chest.

And I'm not directing this at that originator of this thread at all. It's just a general suggestion to new owners of new OR used REs. Part of ownership is to take responsibility to at least learn enough so you can understand the answers you get to the questions you ask & then can act on them to make the bike happy. Otherwise why ask?

Too late. The en-ess-ay already logged it into their data base and will forever know you want to change your battery.

Ha! They've alReady got enough on me to send in the black heeliocopters. They'll probably tell the DMV all the mods I've made & they'll come in the dark of night ("It was a dark & stormy night. The rain dripped....") & smash my bike. And then the IRS will audit me for voting for Goldwater.

Pulled the carburetor off today for cleaning, and to see just how it was jetted. Continuing on the odd train, it looks like the main jet is a 130 (!). Didn't get a good look at the pilot jet. Honestly, I'm not even sure it was marked.

I gave the float bowl and jets a good cleaning, then reinstalled. Battery seems to be behaving today, so I kicked her over and got her running after I messed around with the throttle idle screw (the sprung screw the throttle spring rests on). Idled fine after I pulled the enricher (choke knob) out all the way.

Tried messing around with the airscrew (little flathead screw under the brass throttle plate, right?) to get the idle to sound right-- it didn't like that and died with a bit of dusty smoke from the air filter. Huh.

Questions-- is the jetting waaay too high? Running stock BS-29 Mikuni carb with the K&N air-filter, and what looks like the classic exhaust. I live in the rural Northeast, so I'm not exactly up there with elevation. Superchuck, you mentioned in another thread that you're running a 120 main jet-- should I be jetting this thing down? Seems to have a pretty hard time starting.

Also, in regards to the air screw, how tight is tightened all the way? When I tighten it to where it feels like it was before, seems like I hit a small spring (bit of a creaking sound). Should I keep twisting until it's locked down all the way before backing it off, or is the spring the extent of how far I should screw the airscrew in?

Pulled the carburetor off today for cleaning, and to see just how it was jetted. Continuing on the odd train, it looks like the main jet is a 130 (!). Didn't get a good look at the pilot jet. Honestly, I'm not even sure it was marked.

Thanks guys,RP

That main jet is way too big. I don't know why there's a 130 in there, but it's too big.

Yes. The pilot jet is marked. You might need a magnifying glass. It should be a 15 or a 17.5 - must know what it is.

Tried messing around with the airscrew (little flathead screw under the brass throttle plate, right?) to get the idle to sound right-- it didn't like that and died with a bit of dusty smoke from the air filter. Huh.

Thanks guys,RP

I think you're talking about the fuel/air mixture screw, but I'm not sure. That carb doesn't have a throttle plate.

Also, in regards to the air screw, how tight is tightened all the way? When I tighten it to where it feels like it was before, seems like I hit a small spring (bit of a creaking sound). Should I keep twisting until it's locked down all the way before backing it off, or is the spring the extent of how far I should screw the airscrew in?

Thanks guys,RP

You don't want to be cranking that screw in like you're tightening a bolt. You don't need to "lock it down". You want to just gently bottom it out. You should be able to gently feel it bottom out. Then watch the slot & count the half turns out (CCW).

I've filed a little mark on a tiny brass handled screwdriver that matches the tip so I don't have to contort my head & neck like Rubber Man to see the slot in the screw. I just watch the handle.

Thanks for the help-- really, I think this may be what's been driving me crazy about this bike!

Reading through some of the other collected wisdom on jetting, sounds like my carb is set WAY rich. Explains why the sparkplug has come out black and oily after the little amount of time I've run it. May also be the cause of my sprag woes (oh yeah, still have to deal with that), since I'm guessing running that rich caused a lot of backfiring.

I'm not as clear on how to adjust the needle height-- would I have to open the top of the carb to get to it? Sorry, still learning >.<

Sorry, when I said I pulled the enricher out to help it idle, I meant the black choke knob. I saw a tutorial that explained that Mikuni carbs technically have "enrichers" rather than "chokes." My fault

I have a 17.5 pilot in a similar setup. My mixture screw is about 1/2 to 3/4 out. I suggest getting a good idle first. That main jet does sound too big but has nothing to really do on an idle. The idle circuit is generally pilot jet and circuit, mixture screw/needle, air and fuel float level. Assuming the circuits are clean, and there are no air leaks, that leaves the jet, screw or float level (I believe the level should be 17.1 mm).

Mikuni jet can be found on eBay, our host, jets r us and are not interchangeable generally. My carb notes are here: